CRSF_FRAMETYPE_DEVICE_PING

Device Ping

The host (handset) sends an extended frame of type CRSF_FRAMETYPE_DEVICE_PING to discover the connected device and the number of config parameters available. If a CRSF device receives a device ping request with its device type in the extended destination (or broadcast), it must reply with a CRSF_FRAMETYPE_DEVICE_INFO even if it has no configurable parameters.

The host should expect a plurality of CRSF_FRAMETYPE_DEVICE_INFO responses depending on the number of currently connected devices, differentiated by their Extended Source fields.

HOST: C8 04 28 00 EA 54
C8 = sync
04 = len
28 = type
00 EA = extended packet
        00 = CRSF_ADDRESS_BROADCAST (extended destination)
        EA = CRSF_ADDRESS_RADIO_TRANSMITTER (extended source)
54 = CRC